Water-repellent, breathable films have a wide field of application. Depending on the water vapor permeability these films are used in the hygiene sector for diapers or incontinence products or in the construction sector as part of a building sheeting or for the production of adhesive tapes which by way of example are used for the adhesive bonding of films or sheets for preparing a building sheeting.
In the hygiene sector liquid-repellent and/or liquid-impermeable, breathable films are arranged preferably as protective films, in particular underwear-protecting films arranged as external surface, facing away from the body, of a hygiene product or incontinence product, because essential properties are not only impermeability to aqueous liquids but also dissipation of the water vapor that is emitted from the skin region covered by the respective product, for example through sweating. Accordingly these protective films of hygiene products or of incontinence products must, although they are impermeable to aqueous liquids, in particular water, have an adequate water vapor transmission rate, i.e. must be breathable.
In the construction sector, in particular in the external region of a house, e.g. on roofs or on facades, films are often installed in the form of large-surface-area sheet material as “wind proofing” or “rain proofing” material. The arrangement of these protective covering materials is mostly above the insulation layer and below the actual external covering or external layer composed by way of example of tiles, fiber-reinforced concrete panels, or the like. These protective covering sheets are usually laid so as to overlap, and at least the resultant joints are adhesive-bonded with single-sided adhesive tapes.
This avoids air flows or moisture penetration through any open joints in the region of the insulation layer, even if wind, snow, or rain penetrates through the external layer. These air flows comprising cold and/or moist external air reduce the effect of insulation, and this should as far as possible be avoided.
On the other hand, these protective coverings, i.e. large-surface-area sheeting material, and also the adhesive tapes, must at the same time be permeable to water vapor, in order to ensure outward transport of moisture from the interior of the house, and thus avoid the risk of rot and mold formation.
The breathable films used for this purpose, known from the prior art, and products produced therefrom, exhibit disadvantages in their handling.
By way of example, adhesive tapes, in particular with appropriately oriented water vapor transmission rate and with substrate layers made of known breathable, multilayer films, can have a tendency toward delamination, and this can lead to permeability, e.g. in the case of roof linings.
It was therefore an object of the present invention to provide a breathable film that repels aqueous liquids, preferably water, and that ensures excellent handling and long-lasting quality, and the water vapor transmission rate of which can be adjusted in accordance with the requirements of the respective intended purpose.